Illumination device for a display having a plate shaped optical unit with transmissive and reflective sections where light beams from mutually different directions are incident thereon

ABSTRACT

An illumination device includes: a plurality of light source assemblies; and a plate-shaped optical unit on which light source light beams from the plurality of light source assemblies are incident from mutually different directions, and the plate-shaped optical unit is sectioned into a reflection surface and a transmission surface in accordance with an incident light intensity distribution of each of the light source light beams. Then, transmitted light having passed through the plate-shaped optical unit among the light source light beams and reflected light having been reflected by the plate-shaped optical unit among the light source light beams are emitted with directions aligned, and a boundary between the transmission surface and the reflection surface in the plate-shaped optical unit is formed at a position where incident light intensities of the light source light beams individually from the plurality of light source assemblies have substantially equal values to each other.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. 371 andclaims the benefit of PCT Application No. PCT/JP2020/035485, having aninternational filing date of 18 Sep. 2020, which designated the UnitedStates, which PCT application claimed the benefit of Japanese PatentApplication No. 2019-173429, filed 24 Sep. 2019, the entire disclosuresof each of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an illumination device and a displaydevice, and in particular to an illumination device in which a pluralityof light source assemblies is provided, light source light beamsindividually from the plurality of light source assemblies are incidentfrom different directions, and emission directions of incident lightbeams are aligned, and a display device including the illuminationdevice in a light source unit.

BACKGROUND ART

An illumination device applicable as a light source unit of a displaydevice such as a projector is required to achieve both reduction of asize of a luminous flux emitted from the illumination device andsuppression of a decrease in luminance. In this regard, as theillumination device, a technique has been proposed in which a lightsynthesizing member including transmission areas and strip-shapedreflective films alternately is provided to reduce a luminous flux sizeof illuminating light (see, for example, Patent Document 1).

Furthermore, as an illumination device, a technique has been proposed inwhich a light composite unit in which striped mirrors having mutuallydifferent surface directions are alternately crossed is provided tosuppress an increase in a composite bundle of rays (see, for example,Patent Document 2).

CITATION LIST Patent Document

-   Patent Document 1: Japanese Patent Application Laid-Open No.    2010-102049-   Patent Document 2: Japanese Patent Application Laid-Open No.    2018-21990

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Such an illumination device is desired to further reduce a size of aluminous flux emitted from the illumination device while suppressing adecrease in luminance.

An object of the present disclosure is to provide an illumination devicecapable of further reducing a size of an emitted luminous flux, and adisplay device including the illumination device.

Solutions to Problems

The present disclosure is, for example,

-   -   (1) an illumination device including:    -   a plurality of light source assemblies; and    -   a plate-shaped optical unit on which light source light beams        from the plurality of light source assemblies are incident from        mutually different directions, the plate-shaped optical unit        being sectioned into a reflection surface and a transmission        surface in accordance with an incident light intensity        distribution of each of the light source light beams, in which    -   transmitted light having passed through the plate-shaped optical        unit among the light source light beams and reflected light        having been reflected by the plate-shaped optical unit among the        light source light beams are emitted with directions aligned,        and    -   a boundary between the transmission surface and the reflection        surface in the plate-shaped optical unit is formed at a position        where incident light intensities of the light source light beams        individually from the plurality of light source assemblies have        substantially equal values to each other.

Furthermore, the present disclosure may be

-   -   (2) an illumination device including:    -   a plurality of light source optical units configured to emit        light beams derived from a plurality of single light sources in        a state where directions are aligned with each other; and    -   a first plate-shaped optical unit on which the light beams from        the plurality of light source optical units are incident from        mutually different directions, the first plate-shaped optical        unit being sectioned into a reflection surface and a        transmission surface in accordance with an incident light        intensity distribution of each of the light beams, in which    -   transmitted light having passed through the first plate-shaped        optical unit among the light beams and reflected light having        been reflected by the first plate-shaped optical unit among the        light beams are emitted with directions aligned,    -   a boundary between the transmission surface and the reflection        surface in the first plate-shaped optical unit is formed at a        position where incident light intensities of light beams        individually from the plurality of light source optical units        have substantially equal values to each other,    -   at least one of the light source optical units includes:    -   a plurality of light source assemblies; and    -   a second plate-shaped optical unit on which light source light        beams from the plurality of light source assemblies are incident        from mutually different directions, the second plate-shaped        optical unit being sectioned into a reflection surface and a        transmission surface in accordance with an incident light        intensity distribution of each of the light source light beams,    -   a boundary between the transmission surface and the reflection        surface in the second plate-shaped optical unit is formed at a        position where incident light intensities of the light source        light beams individually from the plurality of light source        assemblies have substantially equal values to each other, and    -   transmitted light having passed through the second plate-shaped        optical unit among the light source light beams and reflected        light having been reflected by the second plate-shaped optical        unit among the light source light beams are emitted with        directions aligned.

Furthermore, the present disclosure may be

-   -   (3) an illumination device including:    -   a plurality of light source optical units configured to emit        light beams derived from a plurality of single light sources in        a state where directions are aligned with each other; and    -   a plate-shaped optical unit on which the light beams from the        plurality of light source optical units are incident from        mutually different directions, the plate-shaped optical unit        being sectioned into a reflection surface and a transmission        surface in accordance with an incident light intensity        distribution of each of the light beams, in which    -   transmitted light having passed through the plate-shaped optical        unit among the light beams and reflected light having been        reflected by the plate-shaped optical unit among the light beams        are emitted with directions aligned,    -   a boundary between the transmission surface and the reflection        surface in the plate-shaped optical unit is formed at a position        where incident light intensities of light beams individually        from the plurality of light source optical units have        substantially equal values to each other,    -   at least one of the light source optical units includes:    -   a first polarized light source assembly and a second polarized        light source assembly that are configured to mutually emit        S-polarized light, and a ½ wavelength plate configured to        convert the S-polarized light emitted from the first polarized        light source assembly into P-polarized light; and    -   a polarization dichroic mirror configured to allow the        P-polarized light to pass through and configured to reflect the        S-polarized light from the second polarized light source        assembly, and    -   a multiplexed light beam of the P-polarized light having passed        through the polarization dichroic mirror and the S-polarized        light reflected by the polarization dichroic mirror is emitted.

Furthermore, the present disclosure may be

-   -   (4) a display device including:    -   a light source unit;    -   a light modulation-synthesis system configured to modulate and        synthesize incident light;    -   an illumination optical system configured to guide light emitted        from the light source unit to the light modulation-synthesis        system; and    -   a projection optical system configured to project an image        emitted from the light modulation-synthesis system, in which    -   the light source unit is the illumination device according        to (1) described above.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a view illustrating an example of a configuration of anillumination device according to a first embodiment. FIG. 1B is a viewillustrating an example of a light intensity distribution of a lightsource light beam incident on a plate-shaped optical unit and an exampleof a formation pattern of a transmission surface and a reflectionsurface, in the example of the illumination device illustrated in FIG.1A.

FIG. 2A is a view illustrating an example of a first intensity center G1a and a second intensity center G1 b, and a straight line M connectingG1 a and G1 b. FIG. 2B is a graph illustrating an example of arelationship between a position along the straight line M and anintensity of an incident light beam from a single light source.

FIG. 3A is a view illustrating an example of a configuration of theillumination device according to the first embodiment. FIG. 3B is a viewillustrating an example of a light intensity distribution of a lightsource light beam incident on a plate-shaped optical unit and an exampleof a formation pattern of a transmission surface and a reflectionsurface, in the example of the illumination device illustrated in FIG.3A.

FIGS. 4A and 4B are views illustrating an example of an incident lightintensity distribution of a light source light beam incident on aplate-shaped optical unit, in an example of the illumination deviceaccording to the first embodiment.

FIG. 5 is a view illustrating an example of a combination of a path of alight source light beam from a light source assembly toward atransmission surface of the plate-shaped optical unit and a path of alight source light beam from the light source assembly toward areflection surface of the plate-shaped optical unit, in the example ofthe illumination device according to the first embodiment.

FIG. 6A is a view illustrating an example of a configuration of theillumination device according to the first embodiment. FIG. 6B is a viewillustrating an example of a light intensity distribution of a lightsource light beam incident on a plate-shaped optical unit and an exampleof a formation pattern of a transmission surface and a reflectionsurface, in the example of the illumination device illustrated in FIG.6A.

FIG. 7 is a view illustrating a configuration of an example of a singlelight source that forms a plurality of light source assemblies.

FIG. 8A is a view illustrating an example of a configuration of anillumination device according to a second embodiment. FIG. 8B is a viewillustrating an example of a light intensity distribution of a lightsource light beam incident on a first plate-shaped optical unit and anexample of a formation pattern of a transmission surface and areflection surface, in the example of the illumination deviceillustrated in FIG. 8A.

FIG. 9A is a view illustrating an example of a configuration of theillumination device according to the second embodiment. FIG. 9B is aview illustrating an example of a light intensity distribution of alight source light beam incident on a first plate-shaped optical unitand an example of a formation pattern of a transmission surface and areflection surface, in the example of the illumination deviceillustrated in FIG. 9A.

FIG. 10A is a view illustrating an example of a configuration of theillumination device according to the second embodiment. FIG. 10B is aview illustrating an example of a light intensity distribution of alight source light beam incident on a first plate-shaped optical unitand an example of a formation pattern of a transmission surface and areflection surface, in the example of the illumination deviceillustrated in FIG. 10A.

FIG. 11A is a view illustrating an example of a light intensitydistribution of a light source light beam incident on a secondplate-shaped optical unit arranged in a light source optical unit and anexample of a formation pattern of a transmission surface and areflection surface, in an example of a configuration of the illuminationdevice according to the second embodiment. FIG. 11B is a viewillustrating an example of a light intensity distribution of a lightsource light beam incident on a third plate-shaped optical unit arrangedin the light source optical unit and an example of a formation patternof a transmission surface and a reflection surface, in an example of aconfiguration of the illumination device according to the secondembodiment.

FIG. 12 is a view illustrating an example of an arrangement pattern oflight emitting elements of a single light source arranged in the lightsource assembly.

FIGS. 13A and 13B are views illustrating an example in which a part of aformation pattern of the transmission surface and the reflection surfaceis enlarged.

FIG. 14A is a view illustrating an example of a configuration of anillumination device according to a third embodiment. FIG. 14B is a viewillustrating an example of a light intensity distribution of a lightsource light beam incident on a plate-shaped optical unit and an exampleof a formation pattern of a transmission surface and a reflectionsurface, in the example of the illumination device illustrated in FIG.14A.

FIG. 15 is a graph illustrating filter characteristics of a polarizationdichroic mirror.

FIG. 16 is a view illustrating an example of a configuration of adisplay device including an illumination device according to the presentdisclosure in a light source unit.

FIG. 17 is a view illustrating a plate-shaped optical unit in anillumination device according to related art.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments and the like of the present disclosure will bedescribed with reference to the drawings.

Note that the description will be given in the following order.

1. Illumination device according to first embodiment

2. Illumination device according to second embodiment

3. Illumination device according to third embodiment

4. Display device

Regarding any of: in one embodiment; between different embodiments; anda display device, configurations having substantially the samefunctional configuration are denoted by the same reference numerals inthe present specification and the drawings, and a redundant descriptionwill be omitted.

The embodiments and the like to be described are preferred specificexamples of the present disclosure. The contents of the presentdisclosure are not limited to these embodiments and the like.

1. First Embodiment

(Illumination Device 1 a)

FIG. 1A is a view illustrating an example of a configuration of anillumination device 1 a (1) according to a first embodiment. Theillumination device 1 a includes a plurality of light source opticalunits 2 and a plate-shaped optical unit 3. The individual light sourceoptical units 2 emit individual light beams derived individually from aplurality of single light sources 5, in a state where directions arealigned with each other. In the illumination device 1 a, any of theindividual light source optical units 2 includes a light source assembly4. In the illumination device 1 a, a first light source assembly 4 a anda second light source assembly 4 b are arranged as a plurality of lightsource assemblies 4.

(Traveling Path of Light Source Light Beam Lw)

In the illumination device 1 a, a light source light beam Lw (Lwa, Lwb)emitted from each of the plurality of light source assemblies 4 isincident on the plate-shaped optical unit 3. The light source lightbeams (Lwa, Lwb) are incident on the plate-shaped optical unit 3 frommutually different directions. The light source light beam Lw passesthrough a transmission surface 6 of the plate-shaped optical unit 3 oris reflected by a reflection surface 7 of the plate-shaped optical unit3, in accordance with a position where the light source light beam Lw isincident on the plate-shaped optical unit 3. The light source light beamLwa from the first light source assembly 4 a is incident from a onesurface 33 a side of the plate-shaped optical unit 3, and passes towardan another surface 33 b side to form transmitted light. The light sourcelight beam Lwb from the second light source assembly 4 b is incident onthe another surface 33 b side of the plate-shaped optical unit 3, and isreflected on the another surface 33 b side to form reflected light. Inthe illumination device 1 a, the transmitted light and the reflectedlight are emitted in a direction away from the plate-shaped optical unit3 in a state where directions are aligned with each other.

Here, a case where predetermined two light beams are emitted withdirection aligned includes a case where the two light beams are emittedin the same direction and a case where the two light beams are emittedin substantially the same direction. This is the same for the second andthird embodiments described later.

(Light Source Assembly 4)

The light source assembly 4 has a structure in which the single lightsources 5 are aligned in a predetermined arrangement pattern. Asillustrated in FIG. 12 , in the example of the illumination device 1 aof FIG. 1A, in both of the first light source assembly 4 a and thesecond light source assembly 4 b, light emitting elements 9 are arrangedin a two-dimensional matrix of four vertical×six horizontal at intervalsfrom each other, and the single light sources 5 are arranged in atwo-dimensional matrix of four vertical×six horizontal. Note that thevertical and horizontal directions of the light source assembly 4 can bedefined as coordinate axis directions of a two-dimensional coordinatesystem in a direction along a plane having a traveling direction oflight as a normal line. In FIG. 12 , a P-axis direction is thehorizontal direction, and a Q-axis direction is the vertical direction.

(Arrangement Number of Single Light Sources 5)

An arrangement number of the single light sources 5 forming the firstlight source assembly 4 a and an arrangement number of the single lightsources 5 forming the second light source assembly 4 b may be the sameor different. Even in a case where an intensity of light from the singlelight source 5 forming the first light source assembly 4 a is differentfrom an intensity of light from the single light source 5 forming thesecond light source assembly 4 b, the light intensities of the firstlight source assembly 4 a and the second light source assembly 4 b canbe matched with each other by appropriately making a difference betweenthe arrangement number of the single light sources 5 of the first lightsource assembly 4 a and the arrangement number of the single lightsources 5 of the second light source assembly 4 b. Furthermore, adesired difference in light intensity can be achieved between the firstlight source assembly 4 a and the second light source assembly 4 b.

(Interval Between Single Light Sources 5)

An interval Wa between adjacent single light sources 5 forming the firstlight source assembly 4 a and an interval Wb between adjacent singlelight sources 5 forming the second light source assembly 4 b may be thesame or different. In a case where an intensity of light from the singlelight source 5 forming the first light source assembly 4 a is differentfrom an intensity of light from the single light source forming thesecond light source assembly 4 b, the light intensities of the firstlight source assembly and the second light source assembly can bematched with each other by appropriately making a difference between theinterval Wa between the adjacent single light sources 5 of the firstlight source assembly 4 a and the interval Wb between the adjacentsingle light sources 5 of the second light source assembly 4 b.Furthermore, a desired intensity difference of a light intensity can beachieved between the first light source assembly 4 a and the secondlight source assembly 4 b.

(Type of Single Light Source 5)

The single light source 5 is not particularly limited as long as lighttraveling in a desired direction can be emitted as a light source lightbeam.

For example, in the example of FIG. 1A, in the single light source 5constituting the light source assembly 4 (4 a, 4 b), a semiconductorlaser is used as the light emitting element 9. Furthermore, in theexample of FIG. 1A, a lens 10 for luminous flux diffusion adjustment isarranged in front of a light emission surface of the light emittingelement 9 constituting the single light source 5. By arranging the lens10, a balance between diffusion and convergence of a light beam emittedfrom the light emitting element 9 is adjusted.

As the light emitting element 9, a light emitting diode 11 or the likecan be used as illustrated in FIG. 7 , in addition to the semiconductorlaser. In a case where the light emitting diode 11 is used as the lightemitting element 9, a condenser lens 12 is preferably arranged in frontof a light emission surface of the light emitting element 9. In a casewhere the single light source 5 includes the light emitting diode 11 andthe condenser lens 12, the single light source 5 forms a collimatedlight source 21. Since the single light source 5 forms the collimatedlight source 21, it is possible to suppress a possibility that a lightbeam Lo generated from the light emitting element 9 is diffused, asillustrated in FIG. 7 .

(Light Intensity Distribution J)

A light intensity distribution J of the light source light beam Lwderived from the single light source 5 forming the light source assembly4 is not particularly limited, and may be a distribution in which anisotropic shape such as a circular shape is a contour shape or adistribution in which an anisotropic shape such as an elliptical shapeis a contour shape as illustrated in FIG. 1B. The light intensitydistribution J of the light source light beam Lw can be appropriatelyselected in accordance with a type of the single light source 5. Notethat the light intensity distribution J indicates a light intensitydistribution formed when the light source light beam Lw derived from thesingle light source 5 reaches the surface 33 b of the plate-shapedoptical unit 3. The contour shape in the light intensity distribution isdefined as an outer edge shape of a portion specified by a region wherean incident intensity is a predetermined value or more in an incidentregion of the light source light beam Lw derived from the single lightsource 5. For example, in the example illustrated in FIG. 1B, the lightintensity distribution is specified as a distribution in which ananisotropic shape of an elliptical shape is a contour shape. In FIGS.1B, 2A, 3B, 6B, 8B, 9B, 10B, 11A, 11B, 13A, 13B, 14B, and 17, the lightintensity distribution J is specified in a region surrounded by a brokenline or a one dotted chain line.

A light intensity distribution of a light source light beam derived froma single light source incorporated in a light source unit of a displaydevice is often a distribution having an anisotropic contour shape. Inconsideration of this point, in the illumination device 1 a, it ispreferable that a first light intensity distribution Ja of the lightsource light beam Lw derived from the single light source 5 forming thefirst light source assembly 4 a and a second light intensitydistribution Jb of a light source light beam derived from the singlelight source 5 forming a second light source in the plate-shaped opticalunit 3 have a distribution having an anisotropic contour shape, from theviewpoint of being easily used as an illumination device incorporated ina light source unit of a display device.

(Main Wavelength of Light Source Light Beam Lw)

A main wavelength (nm) of the light source light beam Lw derived fromthe single light source 5 forming the light source assembly 4 may beappropriately selected in accordance with a purpose. A main wavelengthof the light source light beam Lwa from the first light source assembly4 a and a main wavelength of the light source light beam Lwb from thesecond light source assembly 4 b may be the same or different from eachother. Therefore, a color of the light source light beam Lwa from thefirst light source assembly 4 a and a color of the light source lightbeam Lwb from the second light source assembly 4 b may be the same ordifferent from each other. In a case where the main wavelength of thelight source light beam Lwa from the first light source assembly 4 a andthe main wavelength of the light source light beam Lwb from the secondlight source assembly 4 b are different from each other, light beams ofa plurality of colors can be emitted from the illumination device. Notethat the main wavelength means a wavelength having a maximum value of anemission intensity in an emission spectrum of the light source assembly4.

(Plate-Shaped Optical Unit 3)

The plate-shaped optical unit 3 has a configuration sectioned into thetransmission surface 6 and the reflection surface 7. The transmissionsurface 6 and the reflection surface 7 are formed on the surface 33 b (alight emission surface) on an emission surface side of transmitted lightand reflected light derived from light source light beams, amongsurfaces of the plate-shaped optical unit 3.

A position and a direction of the plate-shaped optical unit 3 aredetermined such that transmitted light passing through the plate-shapedoptical unit 3 and reflected light reflected by the plate-shaped opticalunit 3 are emitted with directions aligned. For example, in the exampleof FIG. 1A, the first light source assembly 4 a and the second lightsource assembly 4 b are arranged such that a traveling direction of thelight source light beam Lwa from the first light source assembly 4 a anda traveling direction of the light source light beam Lwb from the secondlight source assembly 4 b are substantially orthogonal to each other ata position of the plate-shaped optical unit. Then, the plate-shapedoptical unit 3 is oriented such that both the light source light beamsare to be incident at an angle of approximately 45°.

(Transmission Surface 6 and Reflection Surface 7)

In the surface 33 b, the transmission surface 6 and the reflectionsurface 7 are classified in accordance with an incident light intensitydistribution of a light beam from the light source optical unit 2. Inthe illumination device 1 a of the first embodiment, the transmissionsurface 6 and the reflection surface 7 on the surface 33 b of theplate-shaped optical unit 3 are classified in accordance with anincident light intensity distribution of the light source light beam Lwfrom the light source assembly 4.

The incident light intensity distribution of the light source light beamLw from the light source assembly 4 is specified as a distributionindicating a relationship between a position on the surface 33 b of theplate-shaped optical unit 3 and an intensity of the light source lightbeam. The incident light intensity distribution of the light sourceassembly 4 on the surface 33 b of the plate-shaped optical unit is to bea distribution in which intensity distributions (referred to as unitdistributions) of the light source light beams Lw derived fromindividual single light sources 5 forming the light source assembly 4are collected and combined.

In the plate-shaped optical unit 3 of the illumination device of theexample of FIG. 1A, the incident light intensity distribution of thelight source light beam Lwa of the first light source assembly 4 a is adistribution in which the first light intensity distributions Ja arearranged in a lattice shape, and adjacent unit distributions arecontinuous in the horizontal direction (for example, FIG. 4A). Theincident light intensity distribution of the light source light beam Lwbof the second light source assembly 4 b is also a distribution in whichthe second light intensity distributions Jb are arranged in a latticeshape, and adjacent unit distributions are continuous in the horizontaldirection. The incident light intensity distribution of the light sourcelight beam Lwa of the first light source assembly 4 a and the incidentlight intensity distribution of the light source light beam Lwb of thesecond light source assembly 4 b are determined such that the firstlight intensity distribution Ja and the second light intensitydistribution Jb are alternately arranged in an oblique direction andarranged in zigzag as the entire arrangement of the light intensitydistributions, in a case where the incident light intensity distributionof the light source light beam Lwa of the first light source assembly 4a and the incident light intensity distribution of the light sourcelight beam Lwb of the second light source assembly 4 b are combined.Note that the vertical and horizontal directions can be defined ascoordinate axis directions of a two-dimensional coordinate system in adirection along a surface of the plate-shaped optical unit 3. Forexample, in FIG. 1B, an X-axis direction is the horizontal direction,and a Y-axis direction is the vertical direction. This is the same inFIGS. 3B, 6B, 8B, 9B, 10B, 11A, 11B, 13A, 13B, 14B, and 17 .

In an example of the plate-shaped optical unit 3 of the illuminationdevice of FIG. 1A, for both the incident light intensity distribution ofthe first light source assembly 4 a and the incident light intensitydistribution of the second light source assembly 4 b, the incident lightintensity decreases as being separated from a position (an intensitycenter G) where the incident light intensity becomes strongest, in eachunit distribution. An intensity center Ga in the incident lightintensity distribution of the first light source assembly 4 a and anintensity center Gb in the incident light intensity distribution of thesecond light source assembly 4 b are alternately arranged in an obliquedirection in correspondence to the arrangement of the first lightintensity distribution Ja and the second light intensity distributionJb. Furthermore, the unit distribution of the single light source 5 ofthe first light source assembly 4 a partially overlaps with an adjacentunit distribution of the single light source 5 of the second lightsource assembly 4 b. That is, the incident light intensity distributionof the light source light beam Lwa of the first light source assembly 4a partially overlaps with the incident light intensity distribution ofthe light source light beam Lwb of the second light source assembly 4 b.

On the surface 33 b of the plate-shaped optical unit, the incident lightintensity distribution of the light source light beam Lwa from the firstlight source assembly 4 a and the incident light intensity distributionof the light source light beam Lwb from the second light source assembly4 b may be mutually the same or different as illustrated in FIGS. 4A and4B. For example, the incident light intensity distribution shown in theexample of FIG. 4A may be the incident light intensity distribution ofthe light source light beam Lwa from the first light source assembly 4a, and the incident light intensity distribution shown in the example ofFIG. 4B may be the incident light intensity distribution of the lightsource light beam Lwb from the second light source assembly 4 b. FIGS.4A and 4B illustrate a part of incident light intensity distributions oflight source light beams from light source assemblies. FIGS. 4A and 4Bare isogram charts in which an isogram of an intensity of a light sourcelight beam is drawn for every constant value. The incident lightintensity distributions illustrated in the examples of FIGS. 4A and 4Bare mutually different in maximum value of an incident light intensityin a unit distribution and in width of a region where the incident lightintensity exceeds a predetermined value. In the incident light intensitydistribution illustrated in the example of FIG. 4A, the maximum value ofthe incident light intensity is large and the region where the incidentlight intensity exceeds the predetermined value is narrow, as comparedwith those of the incident light intensity distribution illustrated inthe example of FIG. 4B.

(Boundary 8 Between Transmission Surface 6 and Reflection Surface 7)

A boundary 8 between the transmission surface 6 and the reflectionsurface 7 is formed at a position where incident light intensities ofthe light source light beams Lw individually from the plurality of lightsource assemblies 4 have substantially equal values. The incident lightintensity of the light source light beam Lw from each of the lightsource assemblies 4 can be specified on the basis of the incident lightintensity distribution of the light source light beam Lw from each ofthe light source assemblies 4.

As described above, the incident light intensity distribution of thelight source light beam Lwa of the first light source assembly 4 a andthe incident light intensity distribution of the light source light beamLwb of the second light source assembly 4 b are determined such that thelight intensity distributions are arranged in zigzag, in theplate-shaped optical unit 3 of the illumination device 1 a of theexample of FIG. 1A, in a case where the incident light intensitydistribution of the light source light beam Lwa of the first lightsource assembly 4 a and the incident light intensity distribution of thelight source light beam Lwb of the second light source assembly 4 b arecombined. The incident light intensity distribution of the light sourcelight beam Lwa of the first light source assembly 4 a partially overlapswith the incident light intensity distribution of the light source lightbeam Lwb of the second light source assembly 4 wb. In the overlappingportion of the incident light intensity distribution, the boundary 8between the transmission surface 6 and the reflection surface 7 isdefined at a position where the incident light intensities havesubstantially equal values.

(Position at which Incident Light Intensities have Substantially Equalvalues)

The case where the boundary 8 between the transmission surface 6 and thereflection surface 7 is at a position where the incident light intensityof the light source light beam Lwa from the first light source assembly4 a and the incident light intensity of the light source light beam Lwbfrom the second light source assembly 4 b have substantially equalvalues to each other indicates that the following position is theboundary 8 between the transmission surface 6 and the reflection surface7.

In a case where a difference in main wavelength between the light sourcelight beam Lwa from the first light source assembly 4 a and the lightsource light beam Lwb from the second light source assembly 4 b is lessthan 30 nm (a condition A), the boundary 8 between the transmissionsurface 6 and the reflection surface 7 is at a position where thefollowing Formulas 1A to 3A are satisfied.(Ia_f/Ia_max)>0.01  Formula 1A:(Ib_f/Ib_max)>0.01  Formula 2A:0.5<(Ib_f/Ia_f)<2.0  Formula 3A:

However, from the viewpoint of further increasing a ratio of an amountof light used as emitted light to an amount of light incident on theplate-shaped optical unit 3 from the light source assembly 4, it ispreferable that the boundary 8 between the transmission surface 6 andthe reflection surface 7 is a position where the following Formulas 1Bto 3B are satisfied.(Ia_f/Ia_max)>0.03  Formula 1B:(Ib_f/Ib_max)>0.03  Formula 2B:0.5<(Ib_f/Ia_f)<2.0  Formula 3B:

In a case where a difference in main wavelength between the light sourcelight beam Lwa from the first light source assembly 4 a and the lightsource light beam Lwb from the second light source assembly 4 b is 30 nmor more (a condition B), the boundary 8 between the transmission surface6 and the reflection surface 7 is a position where the followingFormulas 4A to 6A are satisfied.(Ia_f/Ia_max)>0.01  Formula 4A:(Ib_f/Ib_max)>0.01  Formula 5A:0.5<((Ib_f/Ib_max)/(Ia_f/Ia_max))<2.0  Formula 6A:

However, from the viewpoint of further increasing a ratio of an amountof light used as emitted light to an amount of light incident on theplate-shaped optical unit 3 from the light source assembly 4, it ispreferable that the boundary 8 between the transmission surface 6 andthe reflection surface 7 is a position where the following Formulas 4Bto 6B are satisfied.(Ia_f/Ia_max)>0.01  Formula 4B:(Ib_f/Ib_max)>0.01  Formula 5B:0.5<((Ib_f/Ib_max)/(Ia_f/Ia_max))<2.0  Formula 6B:

However, as illustrated in FIGS. 2A and 2B, Ia_max is a maximumintensity (W/mm²) of a first light source light beam derived from onesingle light source 5 (a first single light source) selected from thefirst light source assembly 4 a. Ib_max is a maximum intensity of asecond light source light beam derived from one single light source 5 (asecond single light source) selected from the second light sourceassembly. The second light source light beam is a light source lightbeam whose optical axis is adjacent to the first light source light beamat a closest position. Ia_f and Ib_f are at positions on a straight lineM and are an intensity of the first light source light beam and anintensity (W/mm²) of the second light source light beam, respectively,at a position to be a boundary between the transmission surface and thereflection surface.

Note that FIG. 2B is a graph illustrating an example of a profile of anincident light intensity along the straight line M in FIG. 2A. Theincident light intensity mentioned here is an intensity of a light beamincident on the plate-shaped optical unit 3. Furthermore, the profile ofthe incident light intensity indicates a profile of an incident lightintensity of the light source light beam Lwa from the first light sourceassembly 4 a and a profile of an incident light intensity of the lightsource light beam Lwb from the second light source assembly 4 b, on thesurface 33 b of the plate-shaped optical unit 3. In the example of theprofile of the incident light intensity, a horizontal axis indicates aseparation distance (mm) from an origin along the straight line M, witha position, as the origin, giving a maximum intensity of the first lightsource light beam derived from the first single light source. A verticalaxis represents the incident light intensity. The incident lightintensity is specified by, for example, measurement of a radiationdensity (W/mm²) of the light source light beam Lw on the surface 33 b ofthe plate-shaped optical unit 3.

The straight line M indicates a straight line connecting a firstintensity center G1 a and a second intensity center G1 b. The firstintensity center G1 a indicates a center position of an incident lightintensity derived from the first single light source in the incidentlight intensity distribution formed by the light source light beam Lwafrom the first light source assembly 4 a. The second intensity center G1b indicates a center position of an incident light intensity derivedfrom the second single light source.

In the illumination device 1 a according to the first embodiment, ashape of the boundary 8 between the transmission surface 6 and thereflection surface 7 is formed in a smooth wave shape.

However, in the illumination device 1 a according to the firstembodiment, the shape of the boundary 8 between the transmission surface6 and the reflection surface 7 is not limited to the smooth curve aslong as the conditions 1 to 3 described above are satisfied in a casewhere the condition A described above is satisfied, and the conditions 4to 6 described above are satisfied in a case where the above condition Bis satisfied. That is, the shape of the boundary 8 between thetransmission surface 6 and the reflection surface 7 may draw a smoothcurve as illustrated in FIG. 13B, or may be formed in a polygonal lineas illustrated in FIG. 13A.

(Formation of Plate-Shaped Optical Unit 3)

The plate-shaped optical unit 3 can be specifically obtained, forexample, by sectioning and forming the transmission surface 6 and thereflection surface 7 as follows. First, a sheet having opticaltransmissivity is prepared. A material of the sheet is only required tobe appropriately selected in accordance with a purpose. Next, a lightreflecting film is formed in a region corresponding to the reflectionsurface 7 on a surface of the sheet, and the plate-shaped optical unit 3is obtained. The region corresponding to the reflection surface 7 can bespecified by the boundary 8 between the transmission surface 6 and thereflection surface 7 determined according to the above. In this case, inthe plate-shaped optical unit 3, the reflection surface 7 includes alight reflecting film, and the transmission surface 6 includes anon-formation region of the light reflecting film. The light reflectingfilm is only required to be a film having a property of reflectinglight, and examples thereof include a metal film and a dielectricmultilayer film.

(Effect)

According to the illumination device 1 a of the first embodiment, theboundary 8 between the transmission surface 6 and the reflection surface7 is defined at a position where an incident light intensity of thelight source light beam Lwa from the single light source 5 of the firstlight source assembly 4 a and an incident light intensity of the lightsource light beam Lwb of the single light source 5 of the second lightsource assembly adjacent to the single light source 5 have substantiallyequal values. For example, in the example of the illumination deviceillustrated in FIG. 1A, the boundary 8 between the transmission surface6 and the reflection surface 7 is formed in a corrugated shape, and thereflection surface 7 is formed in a corrugated belt-shaped region. In acase where a conventional reflector is used in this example (aconventional example), in place of the plate-shaped optical unit 3, areflector is to be used in which a boundary between a transmissionsurface and a reflection surface is changed from a corrugated shape to alinear shape, and the reflection surface 7 is made into a rectangularregion, as illustrated in FIG. 17 . In a case where the conventionalexample and the example of the illumination device illustrated in FIG.1A are compared, the illumination device illustrated in FIG. 1A has ahigher ratio of an amount of light used as emitted light to an amount oflight incident on the plate-shaped optical unit from the light sourceassembly. This indicates that, in the illumination device of the firstembodiment, more light can be emitted even without requiring an increaseof a luminous flux size, as compared with the case of using theconventional reflector.

As described above, according to the illumination device of the firstembodiment, it is possible to obtain one that can further reduce a sizeof an emitted luminous flux while increasing light emission efficiency(a ratio of an amount of light used as emitted light to an amount oflight incident on the plate-shaped optical unit from the light sourceassembly). Moreover, in the illumination device of the first embodiment,since the plate-shaped optical unit is only required to have thereflection surface and the transmission surface to be formed, the lightemission efficiency can be enhanced without requiring the use of acomplicated structure.

Modified Example 1 of First Embodiment

Regarding the incident light intensity distribution in the illuminationdevice 1 a of the first embodiment, a description has been given to, asan example, a case where the intensity center Ga determined in theincident light intensity distribution of the first light source assemblyand the intensity center Gb determined in the incident light intensitydistribution of the second light source assembly are alternatelyarranged in the oblique direction. The illumination device 1 a of thefirst embodiment is not limited to this, and, as illustrated in theexamples of FIGS. 3A and 3B, the incident light intensity distributionof the first light source assembly and the incident light intensitydistribution of the second light source assembly may have a distributionin which the intensity center Ga determined in the incident lightintensity distribution of the first light source assembly and theintensity center Gb determined in the incident light intensitydistribution of the second light source assembly are alternatelyarranged in the vertical direction. In this case, the illuminationdevice 1 a of the first embodiment can be easily used as a light sourceoptical unit of an illumination device of a second embodiment to bedescribed later (FIG. 9B).

Modified Example 2 of First Embodiment

A description has been given to a case where a light beam incident onthe plate-shaped optical unit 3 is direct light emitted from the lightsource assembly 4, as an example, but the present invention is notlimited to this. As illustrated in FIG. 5 , a light beam reflected by amirror 14 may be incident on the plate-shaped optical unit 3. In a casewhere the light source light beam Lw directed from the light sourceassembly 4 to the plate-shaped optical unit 3 is a light beam reflectedby the mirror 14, an optical path length from the light source assembly4 to the plate-shaped optical unit 3 can be changed, and the incidentlight intensity distribution can be finely adjusted by adjustment or thelike of the number of the mirrors 14 to be installed.

An optical path length between light source assembly 4 and plate-shapedoptical unit 3 indicates a distance from a light emission surface of thesingle light source 5 of the light source assembly 4 to the plate-shapedoptical unit 3 along a traveling direction of a light beam, with acenter of a total luminous flux of a light source light beamconstituting the light source assembly 4 as a reference position. In theexample of FIG. 5 , an optical path length L1 b between the second lightsource assembly 4 b and the plate-shaped optical unit 3 is specified byL1 b (1)+L1 b (2). Note that, in the example of FIG. 5 , an optical pathlength between the first light source assembly 4 a and the plate-shapedoptical unit 3 is Lla.

Note that, in a case where an optical path length between the secondlight source assembly 4 b and the plate-shaped optical unit 3 is largerthan an optical path length between the first light source assembly 4 aand the plate-shaped optical unit 3, it is preferable that the boundary8 between the transmission surface 6 and the reflection surface 7 isdefined such that a distance L2 b from the second intensity center G1 bto the boundary 8 along the straight line M is larger than a distance L2a from the first intensity center G1 a to the boundary 8 along thestraight line M, from the viewpoint of improving a balance betweenintensities of the light source light beam Lwa from the first lightsource assembly 4 a and the light source light beam Lwb from the secondlight source assembly 4 b. From the same viewpoint, in a case where anoptical path length between the second light source assembly 4 b and theplate-shaped optical unit 3 is smaller than an optical path lengthbetween the first light source assembly 4 a and the plate-shaped opticalunit 3, it is preferable that the boundary 8 between the transmissionsurface 6 and the reflection surface 7 is defined such that the distanceL2 b from the second intensity center G1 b to the boundary 8 along thestraight line M is smaller than the distance L2 a from the firstintensity center G1 a to the boundary 8 along the straight line M.

Modified Example 3 of First Embodiment

In the illumination device 1 a of the first embodiment, in a case wherea value Ia_max/Pa is larger than a value Ib_max/Pb, the distance Lb2 ispreferably larger than the distance L2 a from the viewpoint of enhancingthe light emission efficiency. Furthermore, from the same viewpoint, inthe illumination device 1 a of the first embodiment, in a case where thevalue Ia_max/Pa is smaller than the value Ib_max/Pb, the distance Lb2 ispreferably smaller than the distance L2 a.

The value Ia_max/Pa is a value obtained by dividing an intensity (amaximum intensity) Ia_max at the first intensity center G1 a by incidentpower (hereinafter, simply referred to as power) Pa derived from thefirst single light source. The value Ib_max/Pb is a value obtained bydividing a maximum intensity Ib_max at the second intensity center G1 bby power Pb derived from the second single light source. Note that thepower Pa and the power Pb are relative ratio values. That is, one of Paand Pb is set to 1.0, and another one is specified as a relative value.

Modified Example 4 of First Embodiment

In the example of the illumination device 1 a of FIG. 1A, the firstlight intensity distribution Ja and the second light intensitydistribution Jb recognized when light beams from the first light sourceassembly and the second light source assembly are incident on thesurface 33 b of the plate-shaped optical unit 3 have an anisotropiccontour shape in which directions are the same. However, theillumination device 1 a of the first embodiment is not limited to this.

That is, as illustrated in FIGS. 6A and 6B, the first light sourceassembly and the second light source assembly may be arranged such thatthe first light intensity distribution Ja and the second light intensitydistribution Jb recognized on the surface 33 b of the plate-shapedoptical unit 3 have an anisotropic contour shape in which directions aredifferent from each other. In the examples of FIGS. 6A and 6B, incomparison between the first light intensity distribution Ja and thesecond light intensity distribution Jb, both have a distribution havingan elliptical contour shape, and major axis directions are differentfrom each other.

In this case, the boundary 8 is formed so as to surround a periphery ofthe second light intensity distribution Jb, and a part or the whole ofthe boundary 8 has a corrugated shape.

By including such an illumination device in the first embodiment, adegree of freedom in designing the first light source assembly and thesecond light source assembly can be further improved.

2. Second Embodiment

(Illumination Device 1 b)

FIG. 9A is a view illustrating an example of a configuration of anillumination device 1 b (1) according to the second embodiment. Theillumination device 1 b includes a plurality of light source opticalunits 2 and a first plate-shaped optical unit 3 a (3). Similarly to thefirst embodiment, the individual light source optical units 2 emitindividual light beams derived individually from a plurality of singlelight sources 5, in a state where directions are aligned with eachother. In the example of the illumination device 1 b of FIG. 9A, a firstlight source optical unit 2 a and a second light source optical unit 2 bare provided as the light source optical units 2. In the illuminationdevice 1 b, the illumination device 1 a according to the firstembodiment is adopted as at least one of the light source optical units2.

(Traveling Path of Light Source Light Beam Lw)

In the illumination device 1 b, light beams emitted individually fromthe plurality of light source optical units 2 are incident on the firstplate-shaped optical unit 3 a. The light beams are incident on the firstplate-shaped optical unit 3 a from mutually different directions.Further, the light beam passes through a transmission surface 6 of thefirst plate-shaped optical unit 3 a or is reflected by a reflectionsurface 7 of the first plate-shaped optical unit 3 a, in accordance witha position where the light beam is incident on the first plate-shapedoptical unit 3 a. A light beam from the first light source optical unit2 a is incident from a one surface 33 a side of the first plate-shapedoptical unit 3 a and passes toward an another surface 33 b side. A lightbeam from the second light source optical unit 2 b is incident on thesurface 33 b side of the first plate-shaped optical unit 3 a and isreflected on the surface 33 b side. The light source light beam havingpassed through the transmission surface 6 of the first plate-shapedoptical unit 3 a forms transmitted light, and the light source lightbeam reflected by the reflection surface 7 of the first plate-shapedoptical unit 3 a forms reflected light. In the illumination device 1 a,the transmitted light and the reflected light are emitted in a directionaway from the first plate-shaped optical unit 3 a in a state wheredirections are aligned with each other.

(Light Source Optical Unit 2 a)

In the example of the illumination device 1 b of FIG. 9A, the secondlight source optical unit 2 b is an optical system having the sameconfiguration as that of the illumination device 1 a according to thefirst embodiment.

Specifically, the second light source optical unit 2 b includes a firstlight source assembly 4 a and a second light source assembly 4 b, and asecond plate-shaped optical unit 3 b configured to transmit a lightsource light beam from the first light source assembly 4 a and reflect alight source light beam from the second light source assembly 4 b isarranged. Here, in order to distinguish from the first plate-shapedoptical unit 3 a described above, the plate-shaped optical unit 3included in the second light source optical unit 2 b is described as thesecond plate-shaped optical unit 3 b.

The second light source optical unit 2 b emits a light source light beamLwa from the first light source assembly 4 a and a light source lightbeam Lwb from the second light source assembly 4 b, to the firstplate-shaped optical unit 3 a in a state where light traveling methodsare aligned with each other.

The first light source optical unit 2 a includes a third light sourceassembly 4 c. The first light source optical unit 2 a emits a lightsource light beam Lwc from the third light source assembly 4 c, to thefirst plate-shaped optical unit 3 a in a state where light travelingmethods are aligned with each other. As the third light source assembly4 c, one that can be used as the light source assembly 4 of theillumination device 1 a according to the first embodiment is adopted.

(First Plate-Shaped Optical Unit 3 a)

Similarly to the plate-shaped optical unit of the illumination device ofthe first embodiment, the first plate-shaped optical unit 3 a has aconfiguration sectioned into the reflection surface 7 and thetransmission surface 6 in accordance with an incident light intensitydistribution of a light beam from the light source optical unit 2 (FIG.9B). The reflection surface 7 and the transmission surface 6 are formedon the surface 33 b (a light emission surface) on an emission surfaceside of transmitted light and reflected light derived from light sourcelight beams, among surfaces of the first plate-shaped optical unit 3 a.

An incident light intensity distribution of a light beam from the lightsource optical unit 2 is specified as a distribution indicating arelationship between a position on the surface 33 b of the plate-shapedoptical unit 3 and an intensity of the light source light beam.

An incident light intensity distribution of a light beam from the secondlight source optical unit 2 b is a combination of an incident lightintensity distribution of the light source light beam Lwa of the firstlight source assembly 4 a and an incident light intensity distributionof the light source light beam Lwb of the second light source assembly 4b. The incident light intensity distribution of the light source lightbeam Lwa of the first light source assembly 4 a and the incident lightintensity distribution of the light source light beam Lwb of the secondlight source assembly 4 b are determined such that the first lightintensity distribution Ja and the second light intensity distribution Jbadjacent to each other in the vertical direction are alternatelyarranged, and combination units Jx10 of the first light intensitydistribution Ja and the second light intensity distributions Jb arearranged in a lattice shape as the entire arrangement of the lightintensity distributions.

The incident light intensity distribution of the light beam Lwc from thefirst light source optical unit 2 a is determined in accordance with anarrangement of a light intensity distribution (a third light intensitydistribution Jc) of a light source light beam derived from a singlelight source of the third light source assembly 4 c. The third lightintensity distributions Jc are arranged in a lattice shape, and thethird light intensity distribution Jc is determined such that the thirdlight intensity distribution Jc and the combination unit Jx10 of thefirst light intensity distribution Ja and the second light intensitydistribution Jb are alternately arranged in the horizontal direction.

(Boundary 8 between Transmission Surface 6 and Reflection Surface 7)

A boundary 8 between the transmission surface 6 and the reflectionsurface 7 in the first plate-shaped optical unit 3 a is defined at aposition where incident light intensities of light beams from theindividual light source optical units 2 have substantially equal values.

In the second embodiment in which the illumination device of the firstembodiment is used, a light beam incident on the first plate-shapedoptical unit 3 a from the second light source optical unit 2 b is acombination of light source light beams from a plurality of light sourceassemblies. Therefore, there may be a state where a plurality of typesof light beams is adjacent to a light source light beam from the firstlight source optical unit. As described above, in a case where aplurality of types of light source light beams is adjacent to one typeof light source light beam, one light source light beam is reflected bythe first plate-shaped optical unit, and another light source light beamis transmitted, a position at which the incident light intensities ofthe light beams from the individual light source optical units havesubstantially equal values is defined as follows. That is, on the basisof an incident light intensity of one light source light beam selectedaccording to incident light intensities of light source light beams fromthe plurality of light source assemblies and an incident light intensityof a light source light beam from the first light source optical unit,the position at which the incident light intensities of the light beamsfrom the individual light source optical units have substantially equalvalues is defined.

For example, regarding the illumination device of FIG. 9A, a descriptionwill be further given to, as an example, a case where the first lightsource assembly 4 a in the second light source optical unit 2 b is agreen light source (a G light source), the second light source assembly4 b is a red light source (an R light source), and the third lightsource assembly 4 c in the first light source optical unit 2 a is a bluelight source (a B light source). In this case, in an incident lightintensity distribution based on a light beam from the second lightsource optical unit 2 b, for a region where the incident light intensityof the G light source is strong among the incident light intensities ofthe G light source and the R light source, the boundary 8 between thetransmission surface 6 and the reflection surface 7 is defined at aposition where the incident light intensity based on the incident lightintensity distribution of the G light source and the incident lightintensity based on the incident light intensity distribution of the Blight source have substantially equal values to each other.

For a region where the incident light intensity of the R light source isstrong among the incident light intensities of the G light source andthe R light source, the boundary 8 between the transmission surface 6and the reflection surface 7 is defined at a position where the incidentlight intensity based on the incident light intensity distribution ofthe R light source and the incident light intensity based on theincident light intensity distribution of the B light source havesubstantially equal values to each other.

As described in the first embodiment, the position where the incidentlight intensities have substantially equal values indicates a positionwhere Formulas 1A to 3A are satisfied in a case where a condition A issatisfied, and Formulas 3A to 6A are satisfied in a case where acondition B is satisfied. Furthermore, similarly to the firstembodiment, it is preferable that the position where the incident lightintensities have substantially equal values is a position where Formulas1B to 3B are satisfied in a case where the condition A is satisfied andFormulas 4B to 6B are satisfied in a case where the condition B issatisfied.

In the example of the illumination device 1 b illustrated in FIG. 9A, inthe first plate-shaped optical unit 3 a, the transmission surface 6 andthe reflection surface 7 are formed such that the transmission surface 6is formed in a region surrounding a periphery of the individual thirdlight intensity distribution Jc and an outside of the transmissionsurface 6 entirely forms the reflection surface 7.

According to the illumination device 1 b of the second embodiment, it ispossible to obtain one capable of further reducing a size of an emittedluminous flux while increasing a ratio of an amount of light used asemitted light to an amount of light incident on the plate-shaped opticalunit 3 from the light source optical unit 2. Moreover, according to theillumination device of the second embodiment, it is possible to emitlight beams derived from three or more types of light sources in a statewhere directions are aligned with each other. For example, when the Rlight source, the G light source, and the B light source are selected asthe three types of light sources, an RGB light source can be formed.

Modified Example 1 of Second Embodiment

In the example of the illumination device of FIG. 9A, the second lightsource optical unit 2 b is the illumination device 1 a according to thefirst embodiment, and the first light source optical unit is the thirdlight source assembly. The illumination device of the second embodimentis not limited to this, and, as illustrated in FIG. 8A, the first lightsource optical unit 2 a may be the illumination device 1 a according tothe first embodiment, and the second light source optical unit 2 b maybe the third light source assembly 4 c.

Also in this case, similarly to the plate-shaped optical unit of theillumination device of the first embodiment, the first plate-shapedoptical unit 3 a has a configuration sectioned into the reflectionsurface 7 and the transmission surface 6 in accordance with an incidentlight intensity distribution of a light beam from the light sourceoptical unit 2 (FIG. 8B).

An incident light intensity distribution of a light beam from the firstlight source optical unit 2 a is a combination of an incident lightintensity distribution of the light source light beam Lwa of the firstlight source assembly 4 a and an incident light intensity distributionof the light source light beam Lwb of the second light source assembly 4b. The incident light intensity distribution of the light source lightbeam Lwa of the first light source assembly 4 a and the incident lightintensity distribution of the light source light beam Lwb of the secondlight source assembly 4 b are determined such that the first lightintensity distribution Ja and the second light intensity distribution Jbadjacent to each other in the vertical direction are alternatelyarranged, and the combination units J×10 of the first light intensitydistribution Ja and the second light intensity distributions Jb arearranged in a lattice shape as the entire arrangement of the lightintensity distributions. In the example of the illumination device ofFIG. 8A, unlike the example of the illumination device of FIG. 9A,positions of the first light intensity distribution Ja and the secondlight intensity distribution Jb are reversed.

The incident light intensity distribution of the light beam Lwc from thesecond light source optical unit 2 b is determined according to anarrangement of a light intensity distribution (the third light intensitydistribution Jc) of a light source light beam derived from a singlelight source of the third light source assembly 4 c. The third lightintensity distributions Jc are arranged in a lattice shape, and thethird light intensity distribution Jc is determined such that the thirdlight intensity distribution Jc and the combination unit J×10 of thefirst light intensity distribution Ja and the second light intensitydistribution Jb are alternately arranged in the horizontal direction.

A transmission surface and a reflection surface of the plate-shapedoptical unit in the example of the illumination device 1 b illustratedin FIG. 8A are in a state where the transmission surface and thereflection surface in the example of the illumination device of FIG. 9Aare reversed as illustrated in FIG. 8B.

Modified Example 2 of Second Embodiment

In the illumination device 1 b of the second embodiment, as illustratedin FIG. 10A, both the first light source optical unit 2 a and the secondlight source optical unit 2 b may be the illumination device 1 aaccording to the first embodiment.

Specifically, the first light source optical unit 2 a includes the firstlight source assembly 4 a and the second light source assembly 4 b, andthe second plate-shaped optical unit 3 b configured to transmit thelight source light beam Lwa from the first light source assembly 4 a andreflect the light source light beam Lwb from the second light sourceassembly 4 b is arranged. The second light source optical unit 2 bincludes the third light source assembly 4 c and a fourth light sourceassembly 4 d, and a third plate-shaped optical unit 3 c configured totransmit the light source light beam Lwc from the third light sourceassembly 4 c and reflect a light source light beam Lwd from the fourthlight source assembly 4 d is arranged. As the third light sourceassembly 4 c and the fourth light source assembly 4 d, light sourceassemblies having configurations similar to those of the first lightsource assembly 4 a and the second light source assembly 4 b may beused. Similarly to the second plate-shaped optical unit 3 b, the thirdplate-shaped optical unit 3 c may have a configuration in which aboundary between a transmission surface and a reflection surface isformed on the basis of an incident light intensity distribution of alight beam from the light source optical unit 2.

The first light source optical unit 2 a emits the light beam Lwa fromthe first light source assembly 4 a and the light beam Lwb from thesecond light source assembly 4 b, to the first plate-shaped optical unit3 a, in a state where light traveling methods are aligned with eachother by the second plate-shaped optical unit 3 b. Note that the lightbeam Lwb from the second light source assembly 4 b is reflected by amirror 14 and is incident on the second plate-shaped optical unit 3 b.

In the first light source optical unit 2 a, the transmission surface 6and the reflection surface 7 of the second plate-shaped optical unit 3 bare formed as illustrated in FIG. 11A.

The boundary 8 between the transmission surface 6 and the reflectionsurface 7 of the second plate-shaped optical unit 3 b is defined asdescribed in the first embodiment.

The second light source optical unit 2 b emits the light beam Lwc fromthe third light source assembly 4 c and the light beam Lwd from thefourth light source assembly 4 d, to the first plate-shaped optical unit3 a in a state where light traveling methods are aligned with each otherby the third plate-shaped optical unit 3 c. Note that the light beam Lwdfrom the fourth light source assembly 4 d is reflected by the mirror 14and is incident on the third plate-shaped optical unit 3 c.

In the second light source optical unit 2 b, the transmission surface 6and the reflection surface 7 of the third plate-shaped optical unit 3 care formed as illustrated in FIG. 11B. The boundary 8 between thetransmission surface 6 and the reflection surface 7 of the thirdplate-shaped optical unit 3 c is defined as described in the firstembodiment.

The transmission surface 6 and the reflection surface 7 are formed onthe first plate-shaped optical unit 3 a.

The boundary 8 between the transmission surface 6 and the reflectionsurface 7 in the first plate-shaped optical unit 3 a is formed at aposition where incident light intensities of light beams individuallyfrom the plurality of light source optical units 2 have substantiallyequal values. The incident light intensity of the light beam from eachof the light source optical units 2 can be specified on the basis of anincident light intensity distribution of a light beam from each of thelight source optical units 2.

An incident light intensity distribution of a light beam from the firstlight source optical unit 2 a is a combination of an incident lightintensity distribution of the light source light beam of the first lightsource assembly 4 a and an incident light intensity distribution of thelight source light beam of the second light source assembly 4 b. Theincident light intensity distribution of the light source light beam ofthe first light source assembly 4 a and the incident light intensitydistribution of the light source light beam of the second light sourceassembly 4 b are determined to have a distribution state in which acombination (a combined light intensity distribution J×1) of the firstlight intensity distribution Ja and the second light intensitydistribution Jb diagonally adjacent to each other is arranged in thevertical direction and the horizontal direction.

An incident light intensity distribution of a light beam from the secondlight source optical unit 2 b is a combination of an incident lightintensity distribution of a light source light beam of the third lightsource assembly 4 c and an incident light intensity distribution of alight source light beam of the fourth light source assembly 4 d. Theincident light intensity distribution of the light source light beam ofthe third light source assembly 4 c and the incident light intensitydistribution of the light source light beam of the fourth light sourceassembly 4 d are determined to have a distribution state in which acombination (a combined light intensity distribution J×2) of the thirdlight intensity distribution Jc and a fourth light intensitydistribution Jd diagonally adjacent to each other is arranged in thevertical direction and the horizontal direction. Note that the thirdlight intensity distribution Jc and the fourth light intensitydistribution Jd indicate light intensity distributions of a light sourcelight beam of a single light source of the third light source assembly 4c and a light source light beam of a single light source of the fourthlight source assembly 4 d, respectively.

The incident light intensity distributions of light beams from the lightsource optical units 2 a and 2 b in the third plate-shaped optical unit3 c are determined to have a distribution state in which the combinedlight intensity distribution J×1 and the combined light intensitydistribution J×2 are alternately arranged in the vertical direction, asillustrated in FIG. 10B.

As described above, the boundary 8 between the transmission surface 6and the reflection surface 7 in the first plate-shaped optical unit 3 ais defined at a position where incident light intensities of light beamsfrom the individual light source optical units 2 a and 2 b havesubstantially equal values.

According to this illumination device, light beams derived from fourtypes of single light sources can be emitted in a state where directionsare aligned with each other.

3. Third Embodiment

(Illumination Device 1 b)

FIG. 14A is a view illustrating an example of a configuration of anillumination device 1 c (1) according to a third embodiment. Theillumination device 1 c includes a plurality of light source opticalunits 2 and a plate-shaped optical unit 3. Similarly to the firstembodiment, the individual light source optical units 2 emit lightderived individually from a plurality of single light sources in a statewhere directions are aligned with each other. In the example of theillumination device 1 b of FIG. 14A, a first light source optical unit 2a and a second light source optical unit 2 b are provided as the lightsource optical units. In the illumination device 1 b, it is sufficientthat a polarization optical system is provided in at least one of thelight source optical units 2, but here, a case where the polarizationoptical systems are provided in both the light source optical units 2 aand 2 b will be described as an example.

(Traveling Path of Light Source Light Beam)

In the illumination device 1 c, light beams emitted individually fromthe plurality of light source optical units 2 are incident on theplate-shaped optical unit 3. The light beams are incident on theplate-shaped optical unit 3 from mutually different directions. A lightbeam from the first light source optical unit 2 a is incident from a onesurface side of the plate-shaped optical unit 3 and passes towardanother surface side. A light source light beam from the second lightsource optical unit 2 b is incident on the another surface side of theplate-shaped optical unit 3 and is reflected on the another surfaceside. The light source light beam having passed through a transmissionsurface of the plate-shaped optical unit 3 forms transmitted light, andthe light source light beam reflected by the reflection surface of theplate-shaped optical unit forms reflected light. In the illuminationdevice 1 c, the transmitted light and the reflected light are emitted ina direction away from the plate-shaped optical unit 3 in a state wheredirections are aligned with each other.

(Light Source Optical Unit 2)

In the example of the illumination device 1 b of FIG. 14A, the firstlight source optical unit 2 a and the second light source optical unit 2b are a polarization optical system 16 including polarized light sourceassemblies (17 a, 17 b) and (17 c, 17 d) and a polarization dichroicmirror 18.

Specifically, the first light source optical unit 2 a includes: a firstpolarized light source assembly 17 a configured to emit S-polarizedlight; a second polarized light source assembly 17 b configured to emitS-polarized light; a ½ wavelength plate 19 configured to convert theS-polarized light emitted from the first polarized light source assembly17 a into P-polarized light; and the polarization dichroic mirror 18configured to allow the P-polarized light to pass through and configuredto reflect the S-polarized light from the second polarized light sourceassembly.

The second light source optical unit 2 b includes: a third polarizedlight source assembly 17 c configured to emit S-polarized light; afourth polarized light source assembly 17 d configured to emitS-polarized light; a ½ wavelength plate 19 configured to convert theS-polarized light emitted from the third polarized light source assembly17 c into P-polarized light; and the polarization dichroic mirror 18configured to allow the P-polarized light to pass through and configuredto reflect the S-polarized light from the fourth polarized light sourceassembly.

In the first light source optical unit 2 a, S-polarized light from thefirst polarized light source assembly 17 a is converted into P-polarizedlight (a light beam LPa) by passing through the ½ wavelength plate 19.The P-polarized light is incident toward the polarization dichroicmirror 18 and is transmitted through the polarization dichroic mirror18. The S-polarized light (a light beam LSb) from the second polarizedlight source assembly 17 b is reflected by a mirror 20 and incidenttoward the polarization dichroic mirror 18. The S-polarized light isreflected by a surface of the polarization dichroic mirror 18, and hasan optical axis being aligned with that of the P-polarized light. Atthis time, a multiplexed light beam Tw1 of the S-polarized light and theP-polarized light is formed. The multiplexed light beam Tw1 is incidenton the plate-shaped optical unit 3.

In the second light source optical unit 2 b, S-polarized light from thethird polarized light source assembly 17 c is converted into P-polarizedlight (a light beam LPc) by passing through the ½ wavelength plate 19.The P-polarized light is incident toward the polarization dichroicmirror 18 and passes through a surface of the polarization dichroicmirror 18. The S-polarized light (a light beam LSd) from the fourthpolarized light source assembly 17 d is reflected by the mirror 20 andincident toward the polarization dichroic mirror 18. The S-polarizedlight is reflected by a surface of the polarization dichroic mirror 18,and has an optical axis being matched with that of the P-polarizedlight. At this time, similarly to the first light source optical unit 2a, a multiplexed light beam Tw2 of the S-polarized light and theP-polarized light is formed. The multiplexed light beam Tw2 is incidenton the plate-shaped optical unit 3.

(Polarization Dichroic Mirror 18)

For the polarization dichroic mirror 18 included in the first lightsource optical unit 2 a and the second light source optical unit 2 b,one is adopted having such filter characteristics that there is adifference in transmissivity and reflectivity between P-polarized lightand S-polarized light, for light in a predetermined wavelength range.For example, as the polarization dichroic mirror 18, one having filtercharacteristics as illustrated in FIG. 15 can be adopted. An example ofthe polarization dichroic mirror having the filter characteristicsillustrated in FIG. 15 has a property of transmitting P-polarized lightand reflecting S-polarized light between wavelengths A1 and A2,particularly at approximately 455 nm. For example, by combining a filterhaving such characteristics as the polarization dichroic mirror 18 andone configured to emit S-polarized light having wavelengths A1 to A2 asa polarized light source assembly, the first light source optical unitand the second light source optical unit can be specificallyimplemented.

(Plate-Shaped Optical Unit 3)

The plate-shaped optical unit 3 of the illumination device according tothe third embodiment has, similarly to the plate-shaped optical unit ofthe illumination device of the first embodiment, a configurationsectioned into a transmission surface 6 and a reflection surface 7 inaccordance with an incident light intensity distribution of a light beamfrom the light source optical unit. The transmission surface 6 and thereflection surface 7 are formed on a surface 33 b on an emission surfaceside of transmitted light and reflected light derived from light sourcelight beams, among surfaces of the plate-shaped optical unit 3.

An incident light intensity distribution of the multiplexed light beamTw1 from the first light source optical unit 2 a is a combination of anincident light intensity distribution of the P-polarized light from thefirst polarized light source assembly 17 a and an incident lightintensity distribution of the S-polarized light from the secondpolarized light source assembly 17 b. The incident light intensitydistribution of the light source light beam of the first polarized lightsource assembly 17 a and the incident light intensity distribution ofthe light source light beam of the second polarized light sourceassembly 17 b are determined to have a distribution state in whichcombinations of overlapping light intensity distribution Jpa and lightintensity distribution Jsb (an overlapping light intensity distributionJy1) are arranged in a lattice shape. The light intensity distributionJpa and the light intensity distribution Jsb indicate light intensitydistributions of a light source light beam of a single light source ofthe first polarized light source assembly 17 a and a light source lightbeam of a single light source of the second polarized light sourceassembly 17 b, respectively.

An incident light intensity distribution of the multiplexed light beamTw2 from the second light source optical unit 2 b is a combination of anincident light intensity distribution of the P-polarized light from thethird polarized light source assembly 17 c and an incident lightintensity distribution of the S-polarized light from the fourthpolarized light source assembly 17 d. The incident light intensitydistribution of the light source light beam of the third polarized lightsource assembly 17 c and the incident light intensity distribution ofthe light source light beam of the fourth polarized light sourceassembly 17 d are determined to have a distribution state in whichcombinations of overlapping light intensity distribution Jpc and lightintensity distribution Jsd (an overlapping light intensity distributionJy2) are arranged in a lattice shape. The light intensity distributionJpc and the light intensity distribution Jsd indicate light intensitydistributions of a light source light beam of a single light source ofthe third polarized light source assembly 17 c and a light source lightbeam of a single light source of the fourth polarized light sourceassembly 17 d, respectively.

As illustrated in FIG. 14B, the incident light intensity distributionsof light beams from the light source optical units 2 a and 2 b in theplate-shaped optical unit 3 are determined to have a distribution statein which the overlapping light intensity distribution Jy1 and anoverlapping light intensity distribution Jy2 are alternately arranged inan oblique direction.

(Boundary 8 between Transmission Surface 6 and Reflection Surface 7)

A boundary between the transmission surface and the reflection surfacein the first plate-shaped optical unit is defined at a position whereincident light intensities of the multiplexed light beams Tw1 and Tw2 tobe light beams from the individual light source optical units havesubstantially equal values to each other.

As described in the first embodiment, the position where the incidentlight intensities have substantially equal values indicates a positionwhere Formulas 1A to 3A are satisfied in a case where a condition A issatisfied, and Formulas 3A to 6A are satisfied in a case where acondition B is satisfied. Furthermore, similarly to the firstembodiment, it is preferable that the position where the incident lightintensities have substantially equal values is a position where Formulas1B to 3B are satisfied in a case where the condition A is satisfied andFormulas 4B to 6B are satisfied in a case where the condition B issatisfied.

In the plate-shaped optical unit 3, the transmission surface 6 and thereflection surface 7 are formed as illustrated in FIG. 14B on the basisof the criteria described above.

According to the illumination device of the third embodiment, it ispossible to obtain one capable of further reducing a size of an emittedluminous flux while increasing a ratio of an amount of light used asemitted light to an amount of light incident on the first plate-shapedoptical unit from the polarized light source assembly.

Next, an example of a display device according to the present disclosurewill be described.

4. Display Device

In FIG. 16 , a display device 100 shows a configuration example of aprojector that projects an image on a display surface such as a screenS. The display device 100 illustrated in FIG. 16 is a configurationexample of a projector using 3LCD.

Light emitted from a light source unit 101 passes through an integratorlens 200 including a first lens array 200 a and a second lens array 200b, then passes through a polarization conversion element 300 a and acondenser lens 300 b, and is separated for each wavelength range. Theintegrator lens 200 suppresses variations in brightness of a centralportion and brightness of an end portion of the display image.

The light having passed through the condenser lens 300 b is incident ona first reflection dichroic mirror 400 a. Light in a red wavelengthrange is selectively reflected, and light in other wavelength ranges isallowed to pass. As a result, light in the red wavelength range isreflected by the first reflection dichroic mirror 400 a and travelstoward a reflection mirror 500 a side. The light in the red wavelengthrange is further reflected by the reflection mirror 500 a and isincident on a red liquid crystal panel 600 a.

The light in other wavelength ranges having passed through the firstreflection dichroic mirror 400 a is incident on a second reflectiondichroic mirror 400 b. The second reflection dichroic mirror 400 bselectively reflects light in a green wavelength range and allows lightin a blue wavelength range, which is to be light in other wavelengthranges, to pass through. The light in the green wavelength rangereflected by the second reflection dichroic mirror 400 b is incident ona green liquid crystal panel 600 b. Furthermore, the light in the bluewavelength range having passed through the second reflection dichroicmirror 400 b is reflected by reflection mirrors 500 b and 500 c, andthen incident on a blue liquid crystal panel 600 c.

The liquid crystal panels 600 a, 600 b, and 600 c for the respectivecolors modulate light that is individually incident in accordance withan input image signal, and generate signal light of an imagecorresponding to RGB. For the liquid crystal panels 600 a, 600 b, and600 c, for example, a transmissive liquid crystal element using ahigh-temperature polysilicon TFT may be used. The signal light modulatedby each of the liquid crystal panels 600 a, 600 b, and 600 c is incidenton a dichroic prism 700 and synthesized. The dichroic prism 700 isformed in a rectangular parallelepiped obtained by combining fourtriangular prisms so as to reflect red signal light and blue signallight and to transmit green signal light. The signal light of each colorsynthesized by the dichroic prism 700 is incident on a projection lens800 and projected as an image on a display surface such as the screen S.

In the display device 100, the liquid crystal panels 600 a, 600 b, and600 c and the dichroic prism 700 function as a lightmodulation-synthesis system. The light modulation-synthesis system is anoptical system that modulates and synthesizes incident light. Theintegrator lens 200, the polarization conversion element 300 a, thecondenser lens 300 b, the reflection dichroic mirrors 400 a and 400 b,and the reflection mirrors 500 a, 500 b, and 500 c function as anillumination optical system. The illumination optical system is anoptical system that guides light from the light source unit 101 to theliquid crystal panels 600 a, 600 b, and 600 c. Then, the projection lens800 functions as a projection optical system. The projection opticalsystem is an optical system that projects an image emitted from thedichroic prism 700.

In the display device 100, any of the illumination devices of the firstto third embodiments may be provided as the light source unit 101.

According to the illumination devices of the first to third embodiments,it is possible to further reduce a size of an emitted luminous flux.Therefore, the display device according to the present disclosure canreduce a size of the device by including the illumination deviceaccording to the present disclosure.

The projector using the −3LCD has been described as an example of thedisplay device including the illumination device according to thepresent disclosure, but the display device is not limited to this. Forexample, the display device may be a DLP (trademark) projector or thelike.

EXAMPLES Example 1

An illumination device having a configuration as illustrated in FIG. 5was produced. As illustrated in FIGS. 1 and 2A, a plate-shaped opticalunit in which a boundary between a transmission surface and a reflectionsurface is formed into a corrugated shape was prepared. As a singlelight source constituting a first light source assembly and a secondlight source assembly, one including a semiconductor laser and a lensthat suppresses diffusion of laser light was used. The first lightsource assembly and the second light source assembly were positionedsuch that a profile of an incident light intensity distribution along astraight line M in the plate-shaped optical unit was a profile asillustrated in FIG. 2B.

In this device, an optical path length Lla between the first lightsource assembly and the plate-shaped optical unit was 25.8 mm, and anoptical path length L1 b between the second light source assembly andthe plate-shaped optical unit was 87.5 mm.

Furthermore, in the illumination device, in a case where the power Paderived from a single light source constituting the first light sourceassembly was 1.0, the power Pa derived from a single light sourceconstituting the second light source assembly was 0.989. An intensity (amaximum intensity) Ia_max at a first intensity center was 0.589 (W/mm²),and an intensity (a maximum intensity) Ib_max at a second intensitycenter was 0.308 (W/mm²). On the basis of the profile illustrated inFIG. 2B, a position where the profile derived from the single lightsource constituting the first light source assembly and the profilederived from the single light source constituting the second lightsource assembly intersect was defined as a boundary between transmittedlight and reflected light. At this time, both an intensity Ia_f of afirst light source light beam and an intensity Ib_f of a second lightsource light beam at the boundary position were 0.036 (W/mm²).

Comparative Example 1

As illustrated in FIG. 17 , a plate-shaped optical unit in which aboundary between a transmission surface and a reflection surface isformed in a linear shape (a reflection surface is formed in a stripshape) was prepared. A boundary position between the transmissionsurface and the reflection surface was a position along a straight lineM and a position closer to a second intensity center side than inExample 1, and the boundary position was a distance Q illustrated inFIG. 2B.

(Comparison Evaluation)

An amount of light emitted from the illumination devices obtained inExample 1 and Comparative Example 1 was measured. It was confirmed thatan amount of light emitted from the illumination device of Example 1 was3.2% higher than an amount of light emitted from the illumination deviceof Comparative Example 1.

Note that the contents of the present disclosure are not to be construedas being limited by the effects exemplified in the present disclosure.

The present disclosure may have the following configurations.

-   -   (1) An illumination device including:    -   a plurality of light source assemblies; and    -   a plate-shaped optical unit on which light source light beams        from the plurality of light source assemblies are incident from        mutually different directions, the plate-shaped optical unit        being sectioned into a reflection surface and a transmission        surface in accordance with an incident light intensity        distribution of each of the light source light beams, in which    -   transmitted light having passed through the plate-shaped optical        unit among the light source light beams and reflected light        having been reflected by the plate-shaped optical unit among the        light source light beams are emitted with directions aligned,        and    -   a boundary between the transmission surface and the reflection        surface in the plate-shaped optical unit is formed at a position        where incident light intensities of the light source light beams        individually from the plurality of light source assemblies have        substantially equal values to each other,    -   (2) The illumination device according to (1) described above, in        which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light, and    -   a first incident light intensity distribution formed in the        plate-shaped optical unit by a light source light beam from the        first light source assembly is different from a second incident        light intensity distribution formed in the plate-shaped optical        unit by a light source light beam from the second light source        assembly,    -   (3) The illumination device according to (1) or (2) described        above, in which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light, and    -   an optical path length between the first light source assembly        and the plate-shaped optical unit is different from an optical        path length between the second light source assembly and the        plate-shaped optical unit,    -   (4) The illumination device according to any one of (1) to (3)        described above, in which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light,    -   an optical path length between the second light source assembly        and the plate-shaped optical unit is larger than an optical path        length between the first light source assembly and the        plate-shaped optical unit, and    -   in a case of assuming a straight line connecting a first        intensity center and a second intensity center, while a maximum        intensity position is defined as the first intensity center, the        maximum intensity position being of incident light derived from        a first single light source selected from the first light source        assembly in a first incident light intensity distribution formed        by a light source light beam from the first light source        assembly, and a center position is defined as the second        intensity center, the center position being of an incident light        intensity derived from a second single light source that forms        the second light source assembly and is closest to the first        intensity center, and    -   a distance on the straight line from the second intensity center        to the boundary is larger than a distance on the straight line        from the first intensity center to the boundary,    -   (5) The illumination device according to any one of (1) to (4)        described above, in which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light, and    -   a first light intensity distribution of a light source light        beam derived from a single light source forming the first light        source assembly and a second light intensity distribution of a        light source light beam derived from a single light source        forming the second light source assembly are distributions        exhibiting anisotropic contours having different orientations        from each other,    -   (6) The illumination device according to any one of (1) to (5)        described above, in which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light, and    -   an interval between adjacent single light sources forming the        first light source assembly is different from an interval        between adjacent single light sources forming the second light        source assembly,    -   (7) The illumination device according to any one of (1) to (6)        described above, in which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light, and    -   a number of single light sources forming the first light source        assembly is different from a number of single light sources        forming the second light source assembly,    -   (8) The illumination device according to any one of (1) to (7)        described above, in which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light, and    -   in a case of assuming a straight line connecting a first        intensity center and a second intensity center, while a center        position of incident light intensity derived from a first single        light source selected from the first light source assembly is        defined as the first intensity center in a first incident light        intensity distribution formed by a light source light beam from        the first light source assembly, and a center position of an        incident light intensity derived from a second single light        source that forms the second light source assembly and is        closest to the first intensity center is defined as the second        intensity center,    -   a value Ia_max/Ra obtained by dividing an intensity Ia_max at        the first intensity center by power Pa derived from the first        single light source is larger than a value Ib_max/Pb obtained by        dividing an intensity Ib_max at the second intensity center by        power Pb derived from the second single light source, and    -   a distance on the straight line from the second intensity center        to the boundary is larger than a distance on the straight line        from the first intensity center to the boundary.    -   (9) The illumination device according to any one of (1) to (8)        described above, in which    -   the plurality of light source assemblies includes a first light        source assembly serving as a light source of the transmitted        light and a second light source assembly serving as a light        source of the reflected light, and    -   a main wavelength of a light source light beam from the first        light source assembly and a main wavelength of a light source        light beam from the second light source assembly are different        from each other.    -   (10) The illumination device according to any one of (1) to (9)        described above, in which a single light source forming at least        one of the plurality of light source assemblies is a collimated        light source including a light emitting diode and a condenser        lens that is arranged on a light emission surface side of the        light emitting diode.    -   (11) An illumination device including:    -   a plurality of light source optical units configured to emit        light beams derived from a plurality of single light sources in        a state where directions are aligned with each other; and    -   a first plate-shaped optical unit on which the light beams from        the plurality of light source optical units are incident from        mutually different directions, the first plate-shaped optical        unit being sectioned into a reflection surface and a        transmission surface in accordance with an incident light        intensity distribution of each of the light beams, in which    -   transmitted light having passed through the first plate-shaped        optical unit among the light beams and reflected light having        been reflected by the first plate-shaped optical unit among the        light beams are emitted with directions aligned,    -   a boundary between the transmission surface and the reflection        surface in the first plate-shaped optical unit is formed at a        position where incident light intensities of light beams        individually from the plurality of light source optical units        have substantially equal values to each other,    -   at least one of the light source optical units includes:    -   a plurality of light source assemblies; and    -   a second plate-shaped optical unit on which light source light        beams from the plurality of light source assemblies are incident        from mutually different directions, the second plate-shaped        optical unit being sectioned into a reflection surface and a        transmission surface in accordance with an incident light        intensity distribution of each of the light source light beams,    -   a boundary between the transmission surface and the reflection        surface in the second plate-shaped optical unit is formed at a        position where incident light intensities of the light source        light beams individually from the plurality of light source        assemblies have substantially equal values to each other, and    -   transmitted light having passed through the second plate-shaped        optical unit among the light source light beams and reflected        light having been reflected by the second plate-shaped optical        unit among the light source light beams are emitted with        directions aligned,    -   (12) An illumination device including:    -   a plurality of light source optical units configured to emit        light beams derived from a plurality of single light sources in        a state where directions are aligned with each other; and    -   a plate-shaped optical unit on which the light beams from the        plurality of light source optical units are incident from        mutually different directions, the plate-shaped optical unit        being sectioned into a reflection surface and a transmission        surface in accordance with an incident light intensity        distribution of each of the light beams, in which    -   transmitted light having passed through the plate-shaped optical        unit among the light beams and reflected light having been        reflected by the plate-shaped optical unit among the light beams        are emitted with directions aligned,    -   a boundary between the transmission surface and the reflection        surface in the plate-shaped optical unit is formed at a position        where incident light intensities of light beams individually        from the plurality of light source optical units have        substantially equal values to each other,    -   at least one of the light source optical units includes:    -   a first polarized light source assembly and a second polarized        light source assembly that are configured to mutually emit        S-polarized light, and a ½ wavelength plate configured to        convert the S-polarized light emitted from the first polarized        light source assembly into P-polarized light; and    -   a polarization dichroic mirror configured to allow the        P-polarized light to pass through and configured to reflect the        S-polarized light from the second polarized light source        assembly, and    -   a multiplexed light beam of the P-polarized light having passed        through the polarization dichroic mirror and the S-polarized        light reflected by the polarization dichroic mirror is emitted,    -   (13) A display device including:    -   a light source unit;    -   a light modulation-synthesis system configured to modulate and        synthesize incident light;    -   an illumination optical system configured to guide light emitted        from the light source unit to the light modulation-synthesis        system; and    -   a projection optical system configured to project an image        emitted from the light modulation-synthesis system, in which    -   the light source unit is the illumination device according to        any one of (1) to (12) described above.

REFERENCE SIGNS LIST

-   -   1, 1 a, 1 b, 1 c Illumination device    -   2 Light source optical unit    -   2 a First light source optical unit    -   2 b Second light source optical unit    -   3 Plate-shaped optical unit    -   3 a First plate-shaped optical unit    -   3 b Second plate-shaped optical unit    -   3 c Third plate-shaped optical unit    -   33 a One surface of plate-shaped optical unit    -   33 b Another surface of plate-shaped optical unit    -   4 Light source assembly    -   4 a First light source assembly    -   4 b Second light source assembly    -   4 c Third light source assembly    -   4 d Fourth light source assembly    -   5 Single light source    -   6 Transmission surface    -   7 Reflection surface    -   8 Boundary    -   9 Light emitting element    -   10 Lens    -   11 Light emitting diode    -   12 Condenser lens    -   14 Mirror    -   16 Polarization optical system    -   17, 17 a, 17 b, 17 c, 17 d Polarized light source assembly    -   18 Polarization dichroic mirror    -   19 ½ wavelength plate    -   20 Mirror    -   21 Collimated light source

What is claimed is:
 1. An illumination device comprising: a plurality oflight source assemblies; and a plate-shaped optical unit on which lightsource light beams from the plurality of light source assemblies areincident from mutually different directions, the plate-shaped opticalunit being sectioned into a reflection surface and a transmissionsurface in accordance with an incident light intensity distribution ofeach of the light source light beams, wherein transmitted light havingpassed through the plate-shaped optical unit among the light sourcelight beams and reflected light having been reflected by theplate-shaped optical unit among the light source light beams are emittedwith directions aligned, and a boundary between the transmission surfaceand the reflection surface in the plate-shaped optical unit is formed ata position where incident light intensities of the light source lightbeams individually from the plurality of light source assemblies havesubstantially equal values to each other.
 2. The illumination deviceaccording to claim 1, wherein the plurality of light source assembliesincludes a first light source assembly serving as a light source of thetransmitted light and a second light source assembly serving as a lightsource of the reflected light, and a first incident light intensitydistribution formed in the plate-shaped optical unit by a light sourcelight beam from the first light source assembly is different from asecond incident light intensity distribution formed in the plate-shapedoptical unit by a light source light beam from the second light sourceassembly.
 3. The illumination device according to claim 1, wherein theplurality of light source assemblies includes a first light sourceassembly serving as a light source of the transmitted light and a secondlight source assembly serving as a light source of the reflected light,and an optical path length between the first light source assembly andthe plate-shaped optical unit is different from an optical path lengthbetween the second light source assembly and the plate-shaped opticalunit.
 4. The illumination device according to claim 1, wherein theplurality of light source assemblies includes a first light sourceassembly serving as a light source of the transmitted light and a secondlight source assembly serving as a light source of the reflected light,an optical path length between the second light source assembly and theplate-shaped optical unit is larger than an optical path length betweenthe first light source assembly and the plate-shaped optical unit, andin a case of assuming a straight line connecting a first intensitycenter and a second intensity center, while a maximum intensity positionis defined as the first intensity center, the maximum intensity positionbeing of incident light derived from a first single light sourceselected from the first light source assembly in a first incident lightintensity distribution formed by a light source light beam from thefirst light source assembly, and a center position is defined as thesecond intensity center, the center position being of an incident lightintensity derived from a second single light source that forms thesecond light source assembly and is closest to the first intensitycenter, a distance on the straight line from the second intensity centerto the boundary is larger than a distance on the straight line from thefirst intensity center to the boundary.
 5. The illumination deviceaccording to claim 1, wherein the plurality of light source assembliesincludes a first light source assembly serving as a light source of thetransmitted light and a second light source assembly serving as a lightsource of the reflected light, and a first light intensity distributionof a light source light beam derived from a single light source formingthe first light source assembly and a second light intensitydistribution of a light source light beam derived from a single lightsource forming the second light source assembly exhibit anisotropiccontours having different orientations from each other.
 6. Theillumination device according to claim 1, wherein the plurality of lightsource assemblies includes a first light source assembly serving as alight source of the transmitted light and a second light source assemblyserving as a light source of the reflected light, and an intervalbetween adjacent single light sources forming the first light sourceassembly is different from an interval between adjacent single lightsources forming the second light source assembly.
 7. The illuminationdevice according to claim 1, wherein the plurality of light sourceassemblies includes a first light source assembly serving as a lightsource of the transmitted light and a second light source assemblyserving as a light source of the reflected light, and a number of singlelight sources forming the first light source assembly is different froma number of single light sources forming the second light sourceassembly.
 8. The illumination device according claim 1, wherein theplurality of light source assemblies includes a first light sourceassembly serving as a light source of the transmitted light and a secondlight source assembly serving as a light source of the reflected light,and in a case of assuming a straight line connecting a first intensitycenter and a second intensity center, while a center position of anincident light intensity derived from a first single light sourceselected from the first light source assembly is defined as the firstintensity center in a first incident light intensity distribution formedby a light source light beam from the first light source assembly, and acenter position of an incident light intensity closest to the firstintensity center is defined as the second intensity center among centerpositions of incident light intensities derived from individual secondsingle light sources forming the second light source assembly, a valueIa_max/Ra obtained by dividing an intensity Ia_max at the firstintensity center by power Pa derived from the first single light sourceis larger than a value Ib_max/Pb obtained by dividing an intensityIb_max at the second intensity center by power Pb derived from thesecond single light source, and a distance on the straight line from thesecond intensity center to the boundary is larger than a distance on thestraight line from the first intensity center to the boundary.
 9. Theillumination device according to claim 1, wherein the plurality of lightsource assemblies includes a first light source assembly serving as alight source of the transmitted light and a second light source assemblyserving as a light source of the reflected light, and a main wavelengthof a light source light beam from the first light source assembly and amain wavelength of a light source light beam from the second lightsource assembly are different from each other.
 10. The illuminationdevice according to claim 1, wherein a single light source forming atleast one of the plurality of light source assemblies is a collimatedlight source including a light emitting diode and a condenser lens thatis arranged on a light emission surface side of the light emittingdiode.
 11. A display device comprising: a light source unit; a lightmodulation-synthesis system configured to modulate and synthesizeincident light; an illumination optical system configured to guide lightemitted from the light source unit to the light modulation-synthesissystem; and a projection optical system configured to project an imageemitted from the light modulation-synthesis system, wherein the lightsource unit is the illumination device according to claim
 1. 12. Anillumination device comprising: a plurality of light source opticalunits configured to emit light beams derived from a plurality of singlelight sources in a state where directions are aligned with each other;and a first plate-shaped optical unit on which the light beams from theplurality of light source optical units are incident from mutuallydifferent directions, the first plate-shaped optical unit beingsectioned into a reflection surface and a transmission surface inaccordance with an incident light intensity distribution of each of thelight beams, wherein transmitted light having passed through the firstplate-shaped optical unit among the light beams and reflected lighthaving been reflected by the first plate-shaped optical unit among thelight beams are emitted with directions aligned, the transmissionsurface and the reflection surface in the first plate-shaped opticalunit are formed at a position where incident light intensities of lightbeams individually from the plurality of light source optical units havesubstantially equal values to each other, at least one of the lightsource optical units includes: a plurality of light source assemblies;and a second plate-shaped optical unit on which light source light beamsfrom the plurality of light source assemblies are incident from mutuallydifferent directions, the second plate-shaped optical unit beingsectioned into a reflection surface and a transmission surface inaccordance with an incident light intensity distribution of each of thelight source light beams, a boundary between the transmission surfaceand the reflection surface in the second plate-shaped optical unit isformed at a position where incident light intensities of the lightsource light beams individually from the plurality of light sourceassemblies have substantially equal values to each other, andtransmitted light having passed through the second plate-shaped opticalunit among the light source light beams and reflected light having beenreflected by the second plate-shaped optical unit among the light sourcelight beams are emitted with directions aligned.
 13. An illuminationdevice comprising: a plurality of light source optical units configuredto emit light beams derived from a plurality of single light sources ina state where directions are aligned with each other; and a plate-shapedoptical unit on which the light beams from the plurality of light sourceoptical units are incident from mutually different directions, theplate-shaped optical unit being sectioned into a reflection surface anda transmission surface in accordance with an incident light intensitydistribution of each of the light beams, wherein transmitted lighthaving passed through the plate-shaped optical unit among the lightbeams and reflected light having been reflected by the plate-shapedoptical unit among the light beams are emitted with directions aligned,a boundary between the transmission surface and the reflection surfacein the plate-shaped optical unit is formed at a position where incidentlight intensities of light beams individually from the plurality oflight source optical units have substantially equal values to eachother, at least one of the light source optical units includes: a firstpolarized light source assembly and a second polarized light sourceassembly that are configured to mutually emit S-polarized light, and a ½wavelength plate configured to convert the S-polarized light emittedfrom the first polarized light source assembly into P-polarized light;and a polarization dichroic mirror configured to allow the P-polarizedlight to pass through and configured to reflect the S-polarized lightfrom the second polarized light source assembly, and a multiplexed lightbeam of the P-polarized light having passed through the polarizationdichroic mirror and the S-polarized light reflected by the polarizationdichroic mirror is emitted.